Thomas H. Pigford, a strong-minded nuclear engineer who demanded strict safety standards for atomic power plants and brought his independent judgment to bear on the political issues of the nuclear age, died Feb. 28 at his home in Oakland. He was 87.

Mr. Pigford founded and chaired the department of nuclear engineering at UC Berkeley and for 50 years brought his expertise to nuclear reactor designs, nuclear safety, nuclear fuel cycles and the vexing problems raised by the need for long-term disposal of highly radioactive wastes generated by nuclear power plants.

He led a Berkeley research program to develop methods for predicting the long-term behavior of nuclear and chemical wastes from nuclear power plants - particularly those that would have to be stored for tens of thousands of years before their radioactivity would decay to safe levels.

That research resulted in the design of underground nuclear waste repositories, but it was his insistence on planning strong safety standards for the controversial Yucca Mountain nuclear waste disposal site in Nevada that was an important factor in the U.S. Department of Energy's recent decision to seek authorization to abandon the site after 30 years of planning.

Insisted on safety first

Long a supporter of nuclear power, Mr. Pigford constantly focused on the idea that the sources of energy be consistent with concerns for people's safety and health and the environment. He was also vocal about his concern for the proliferation of nuclear weapons and the equipment for making them.

He watched the early planning for the Diablo Canyon plant in California closely, and his constructive criticism was influential in upgrading those plans before the plant began operating in 1985.

A member of the commission that investigated the 1979 accident at the Three Mile Island nuclear power plant in Pennsylvania, he strongly criticized the Nuclear Regulatory Commission for technical errors and for issuing needlessly alarming statements to the public while the accident was in progress.

"My father spoke truth to power, which gained him respect from both proponents and opponents of the nuclear power industry," said his daughter, Julie Pigford Earnest in a statement. "Everything he said or did was based on analysis of the data and not on politics or emotion. He was also insightful about the impact of politics on scientific decisions, and had a sense of how human error and concernscontribute to scientific policy."

Wartime service

He began studies toward his doctorate degree and after wartime service in the Navy and two years at the Oak Ridge National Laboratory, he received his advanced nuclear engineering degree in 1952 from the Massachusetts Institute of Technology, where he was already an associate professor.

In 1959, Mr. Pigford was recruited to UC Berkeley by Nobel laureate Glenn Seaborg and helped spearhead construction of a 1-megawatt research and teaching reactor on the campus. A small nuclear reactor that was finally decommissioned in 1991, the same year he retired to become emeritus and UC Berkeley's Professor of the Graduate School.

Mr. Pigford's first wife, Catherine, died in 1992. He is survived by his second wife, Elizabeth; his daughters from his first marriage, Cynthia Naylor of Durham (Butte County) and Julie Earnest of Portland, Ore.; his stepdaughters, Janvrin Demler of Dedham, Mass., and Laura Weekes of Los Angeles.

A private memorial service will be held in Berkeley on March 27. Contributions may be sent to the Thomas H. Pigford Graduate Fellowship, University Relations, 2080 Addison St., Berkeley, CA 94720, or to Doctors Without Borders USA, P.O. Box 5030, Hagerstown, MD 21741.This obituary has been corrected since it appeared in print.